JP5143606B2 - Charged particle beam irradiation equipment - Google Patents

Description

  The present invention relates to a charged particle beam irradiation apparatus using a scanning method.

2. Description of the Related Art Conventionally, as a charged particle beam irradiation apparatus, for example, a device using a scanning method as described in Patent Document 1 is known. Such a charged particle beam irradiation apparatus includes a scanning electromagnet for scanning a charged particle beam, and a control means for controlling the operation of the scanning electromagnet, and an irradiation line in an irradiation field set on an irradiation object. A continuous irradiation is performed while scanning a charged particle beam along the line.
Japanese Patent Laid-Open No. 2002-22900

  However, in the charged particle beam irradiation apparatus as described above, there is a possibility that unevenness or a decrease may occur in the peripheral portion of the dose distribution of the irradiated charged particle beam (hereinafter simply referred to as “dose distribution”). Here, it is conceivable to control the unevenness and lowering of the edge of the dose distribution by controlling the intensity of the charged particle beam. However, in this case, the scanning method is not realistic because it is necessary to control the intensity of the charged particle beam at high speed and the control becomes complicated.

  Then, this invention makes it a subject to provide the charged particle beam irradiation apparatus which can suppress the nonuniformity and fall of the edge part in the dose distribution of a charged particle beam easily.

  In order to solve the above-mentioned problems, a charged particle beam irradiation apparatus according to the present invention is a charged particle beam irradiation apparatus that continuously irradiates while scanning a charged particle beam along an irradiation line in an irradiation field set on an object to be irradiated. A scanning electromagnet for scanning the charged particle beam, and a control means for controlling the operation of the scanning electromagnet. The control means charges the scanning speed when the charged particle beam is irradiated along the irradiation line. It changes so that the edge part in dose distribution of particle beam may be corrected.

  In this charged particle beam irradiation apparatus, the scanning speed when irradiating a charged particle beam along the irradiation line is changed so that the edge in the dose distribution of the charged particle beam is corrected. That is, the irradiation time of the charged particle beam is lengthened or shortened so that the edge of the dose distribution is corrected. Therefore, it is possible to control the dose distribution at the edge without controlling the intensity of the charged particle beam, and thus it is possible to easily suppress the unevenness and lowering of the edge in the dose distribution.

In addition, the irradiation lines specifically extend in a rectangular wave shape, and three or more rows of first irradiation lines arranged in parallel at a predetermined interval and one end or the other end of adjacent first irradiation lines. And a plurality of second irradiation lines that connect the two. The “rectangular wave shape” here means not only a complete rectangular wave shape but also a substantially rectangular wave shape.

At this time, the control means determines the scanning speed when the charged particle beam is irradiated along the outer first irradiation line among the three or more rows of the first irradiation lines, and the charged particles along the other first irradiation lines. It is preferable to make it slower than the scanning speed when irradiating a line. Here, since the dose of a charged particle beam usually shows a Gaussian distribution, the dose distribution tends to be broadened on the outer edge side, so that the steepness of the dose distribution may be reduced. In this regard, in the present invention, as described above, the scanning speed when the charged particle beam is irradiated along the outer first irradiation line among the three or more rows of the first irradiation lines is set to the other first irradiation lines. The scanning speed is slower than that when the charged particle beam is irradiated along the line. Therefore, the charged particle beam is sufficiently irradiated along the outer first irradiation line. Therefore, it is possible to easily suppress a decrease in the dose distribution at the edge in the direction in which the first irradiation lines are arranged.

  Further, the control means makes the scanning speed when the charged particle beam is irradiated to the end of the first irradiation line slower than the scanning speed when the charged particle beam is irradiated to the end other than the end of the first irradiation line. Alternatively, it is preferably set to 0 for a predetermined time. In this case, the charged particle beam is sufficiently irradiated to the end portion of the first irradiation line. Therefore, it is possible to easily suppress a decrease in the dose distribution at the edge in the direction along the first irradiation line.

  Moreover, it is preferable that a control means speeds up the scanning speed when scanning a charged particle beam along a 2nd irradiation line rather than the scanning speed when scanning a charged particle beam along a 1st irradiation line. When the irradiation line has a rectangular wave shape, a region where the second irradiation line exists and a region where the second irradiation line does not exist are mixed on the end side of the first irradiation line of the irradiation field. For this reason, unevenness between the region where the dose of the irradiated charged particle beam is large and the region where the dose is small is likely to occur on the end side of the first irradiation line of the irradiation field (see, for example, FIG. 7A). In this regard, in the present invention, as described above, the scanning speed along the second irradiation line is made faster than the scanning speed along the first irradiation line. Therefore, the dose of the charged particle beam irradiated along the second irradiation line is suppressed. Therefore, it is possible to easily suppress unevenness between a region where the dose of the charged particle beam is high and a region where the dose of the charged particle beam is small on the end side of the first irradiation line of the irradiation field (see, for example, FIG. 7B).

  Further, the control means sets the scanning speed when irradiating the charged particle beam along the irradiation line at the edge of the dose distribution to be higher than the scanning speed when irradiating the charged particle beam along the other irradiation lines. It is preferable to slow down. In this case, it is possible to easily suppress a decrease in the dose distribution at the edge.

  The irradiation line is configured to include a third irradiation line extending along the outer edge of the irradiation field, and a fourth irradiation line inside the third irradiation line, and the control means includes a third irradiation line. It is preferable that the scanning speed when scanning the charged particle beam along the fourth irradiation line is slower than the scanning speed when scanning the charged particle beam along the fourth irradiation line. In this case, since the charged particle beam is sufficiently irradiated along the third irradiation line, it is possible to easily suppress a decrease in the dose distribution at the edge portion.

At this time, the fourth irradiation line extends in a rectangular wave shape, and three or more rows of fifth irradiation lines arranged in parallel at a predetermined interval are connected to one end or the other end of the adjacent fifth irradiation lines. And a plurality of sixth irradiation lines.

  According to the present invention, it is possible to easily suppress the unevenness and lowering of the edge portion in the dose distribution of the charged particle beam.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, the same or equivalent elements will be denoted by the same reference numerals, and redundant description will be omitted.

  First, the charged particle beam irradiation apparatus according to the first embodiment of the present invention will be described. FIG. 1 is a perspective view of a charged particle beam irradiation apparatus according to the first embodiment of the present invention, and FIG. 2 is a schematic configuration diagram of the charged particle beam irradiation apparatus of FIG. As shown in FIG. 1, the charged particle beam irradiation apparatus 1 is based on a scanning method and is attached to a rotating gantry 12 provided so as to surround a treatment table 11, and around the treatment table 11 by the rotating gantry 12. It can be rotated.

  As illustrated in FIG. 2, the charged particle beam irradiation apparatus 1 continuously irradiates a charged particle beam R toward a tumor (irradiation object) 14 in the body of a patient 13. Specifically, the charged particle beam irradiation apparatus 1 divides the tumor 14 into a plurality of layers in the depth direction (Z direction), and scans the charged particle beam R along the irradiation line L in the irradiation field F set in each layer. Continuous scanning (so-called line scanning) is performed while scanning at a speed V. That is, the charged particle beam irradiation apparatus 1 divides the tumor 14 into a plurality of layers and performs planar scanning on each of these layers in order to form a three-dimensional irradiation field that matches the tumor 14. Thereby, the charged particle beam R is irradiated according to the three-dimensional shape of the tumor 14.

  The charged particle beam R is obtained by accelerating charged particles at a high speed. Examples of the charged particle beam R include a proton beam, a heavy particle (heavy ion) beam, and an electron beam. The irradiation field F is, for example, a region having a maximum size of 200 mm × 200 mm. As shown in FIG. 4, the irradiation field F here has a substantially rectangular outer shape. Note that the shape of the irradiation field F may be various shapes, for example, may be a shape along the shape of the tumor 14.

The irradiation line L is a planned line (virtual line) for irradiating the charged particle beam R. The irradiation line L here extends in a rectangular wave shape, specifically, a plurality of first irradiation lines L ₁ (L _{11 to} L _1n , n is an integer) arranged in parallel at a predetermined interval, It is configured to include a second irradiation line L ₂ a plurality of connecting the one ends or the other ends of the first irradiation line L ₁ adjacent the.

  Returning to FIG. 2, the charged particle beam irradiation apparatus 1 includes a cyclotron 2, focusing electromagnets 3 a and 3 b, monitors 4 a and 4 b, scanning electromagnets 5 a and 5 b, and a fine degrader 8. The cyclotron 2 is a generation source that continuously generates charged particle beams R. The charged particle beam R generated by the cyclotron 2 is transported by the beam transport system 7 to the subsequent focusing electromagnet 3a.

  The converging electromagnets 3a and 3b focus the charged particle beam R to converge. The focusing electromagnets 3a and 3b are arranged on the downstream side of the cyclotron 2 on the irradiation axis of the charged particle beam R (hereinafter simply referred to as “irradiation axis”).

  The monitor 4a monitors the beam position of the charged particle beam R, and the monitor 4b monitors the absolute value of the dose of the charged particle beam R and the dose distribution of the charged particle beam R. The monitor 4a is disposed between the focusing electromagnets 3a and 3b, for example, on the irradiation axis, and the monitor 4b is disposed on the downstream side of the focusing electromagnet 3b, for example, on the irradiation axis.

  The scanning electromagnets 5a and 5b are for scanning the charged particle beam R. Specifically, the irradiation position of the charged particle beam R passing therethrough is moved in the irradiation field by changing the magnetic field according to the applied current. The scanning electromagnet 5a scans the charged particle beam R in the X direction (direction orthogonal to the irradiation axis) of the irradiation field F, and the scanning electromagnet 5b is the Y direction (direction orthogonal to the irradiation axis and the X direction) of the irradiation field F. The charged particle beam R is scanned. These scanning electromagnets 5a and 5b are arranged between the converging electromagnet 3b and the monitor 4b on the irradiation axis. In some cases, the scanning electromagnet 5a scans the charged particle beam R in the Y direction, and the scanning electromagnet 5b scans the charged particle beam R in the X direction.

  The fine degrader 8 is for irradiating each layer of the tumor 14 divided into a plurality of layers in the depth direction with the charged particle beam R. Specifically, the fine degrader 8 changes the energy loss of the charged particle beam R that passes therethrough and adjusts the arrival depth of the charged particle beam R in the body of the patient 13, so that each of the divided layers The arrival depth of the charged particle beam R is adjusted to one layer.

  The charged particle beam irradiation apparatus 1 includes a control device (control means) 6. This control device 6 is electrically connected to the monitor 4b and the scanning electromagnets 5a and 5b, and based on the absolute value and dose distribution of the charged particle beam R monitored by the monitor 4b, the scanning electromagnet 5a, The operation of 5b is controlled (details will be described later).

  Next, the operation of the charged particle beam irradiation apparatus 1 described will be described with reference to the flowchart shown in FIG.

  In the charged particle beam irradiation apparatus 1, the tumor 14 is divided into a plurality of layers in the depth direction, and the charged particle beam R is irradiated toward the irradiation field F set in the one layer. By repeating this for each layer, the charged particle beam R is irradiated along the three-dimensional shape of the tumor 14.

  Here, when irradiating the charged particle beam R, the controller 6 controls the scanning electromagnets 5a and 5b to scan the charged particle beam R in parallel along the irradiation line L of the irradiation field F, and The scanning speed is changed so that the edge (here, the outer edge) in the dose distribution is corrected. Specifically, the control device 6 controls the scanning electromagnets 5a and 5b to execute the following operations.

That is, as shown in FIG. 4 (a), first, while irradiating a charged particle beam R at one end of the outer side of the first irradiation line L ₁₁ (the proximal end of the irradiation line L) and the combined irradiation point, the predetermined time t Scanning is stopped (scanning speed 0) during ₁ (S1). The predetermined time t ₁ is a time relating to the half-value width D of the charged particle beam R and a scanning speed V ₁₁ to be described later, as shown in the following expression (1).
t ₁ = α ₁ × D / V ₁₁ (where 0 <α ₁ <1) (1)

Subsequently, as shown in FIG. 4 (b), along the first irradiation line _{L 11,} it is continuously irradiated while scanning the charged particle beam R at a scanning speed _{V 11} (S2). Then, as shown in FIG. 4 (c), when the irradiation point of the charged particle beam R reaches the other end of the first irradiation line L _11, and stops the scanning of the charged particle beam R by a predetermined time t ₁ (S3).

Subsequently, as shown in FIG. 4 (d), along a second irradiation line L _2, it is continuously irradiated while scanning the charged particle beam R at a scan rate V ₂ (S4). The scanning speed V ₂ is set faster than the scanning speed V ₁₂ to be described later. Then, as shown in FIG. 4 (c), when the irradiation point of the charged particle beam R reaches the other end of the first irradiation line L _12, and stops the scanning of the charged particle beam R by a predetermined time t ₂ (S5). The predetermined time t _2, as shown in the following equation (2), there is a time for the half-value width D and below the scanning speed V ₁₂ Metropolitan of the charged particle beam R.
t ₂ = α ₂ × D / V ₁₂ (where 0 <α ₂ <1) (2)

Subsequently, as shown in FIG. 5 (a), along the first irradiation line _{L 12,} it is continuously irradiated while scanning the charged particle beam R at a scanning speed _{V 12} (S6). The scanning speed _{V 12} is set faster than the scanning speed _{V 11.} In other words, the scanning speed _{V 11} along the first irradiation line _{L 11} has become slower than the scanning speed _{V 12} along the first irradiation line _{L 12.}

Subsequently, when the irradiation point of the charged particle beam R reaches the end of the first irradiation line L _12, and stops the scanning of the charged particle beam R by a predetermined time t ₂ (S7). Then, along the second irradiation line L _2, it is continuously irradiated while scanning the charged particle beam R at a scan rate V ₂ (S8).

Subsequently, the S5~S8 repeated for a predetermined number of times, when the irradiation point of the charged particle beam R at one end of the first irradiation line L _1n opposite to the first irradiation line L ₁₁ has reached, the charged particle beam R scanning only during a predetermined time _{t n} stopped (S9). The predetermined time t _n is a time relating to the half-value width D of the charged particle beam R and a scanning speed V _1n described later, as shown in the following expression (3).
t _n = α _n × D / V _1n (where 0 <α _n <1) (3)

Then, as shown in FIG. 5B, the charged particle beam R is continuously irradiated along the first irradiation line L _1n while scanning the charged particle beam R at a scanning speed V _1n slower than the scanning speed V ₁₂ (S10). Finally, as shown in FIG. 5C, when the irradiation point of the charged particle beam R reaches the other end of the first irradiation line _L1n (end of the irradiation line), scanning of the charged particle beam R is performed for a predetermined time. It stops only for t _n (S11). Thereby, irradiation of the charged particle beam R along the irradiation line L of the irradiation field F is completed.

6A shows a dose distribution in the conventional charged particle beam irradiation apparatus, FIG. 6B shows a dose distribution in the charged particle beam irradiation apparatus in FIG. 1, and FIG. 6C. These are the comparison figures of FIG. 6 (a), (b). In the drawing, dose distributions B0 and B1 indicate the dose distribution (total dose distribution) of the charged particle beam R, and dose distributions B0 _L and B1 _L indicate only the dose distribution along each irradiation line L. .

  Since the dose (intensity) of the charged particle beam R exhibits a Gaussian distribution, as shown in FIG. 6A, in the conventional charged particle beam irradiation apparatus, the dose distribution B0 decreases at the edge (the dose distribution B0 Steepness is reduced). That is, inside the dose distribution B0, uniformity can be maintained due to the influence (overlap) of the charged particle beam R irradiated along the adjacent irradiation line L, but the edge (contour) is gently inclined. The hem will spread.

In contrast, in the charged particle beam irradiation apparatus 1 of the present embodiment, as described above, the control device 6, the charged particles along the outside of the first irradiation line L _11, L _1n of the first irradiation line L ₁ The scanning speeds V ₁₁ and V _1n when irradiating the line R are made slower than the scanning speed V ₁₂ when irradiating the charged particle beam R along the other first irradiation lines. Therefore, the irradiation time of the charged particle beam R along the first irradiation lines L ₁₁ and L _1n becomes longer, and the charged particle beam R is sufficiently irradiated along the first irradiation lines L ₁₁ and L _1n. . Thus, FIG. 6 (b), the (c), the In the dose distribution B1 by the charged particle irradiation apparatus 1, peripheral portions of the first irradiation line L ₁ are arranged direction (lateral direction in FIG. 4) As a result, the dose distribution B1 rises sharply, and it is possible to suppress the decrease at the edge.

Further, the charged particle beam irradiation apparatus 1, as described above, the control device 6, when irradiating a charged particle beam R to the end of the first irradiation line L ₁ (position of the one end and the other end), a charged particle beam the scanning of R only for a predetermined time t ₁ has stopped. Therefore, in the first end portion of the irradiation line L _1, the irradiation time of the charged particle beam R is sufficiently irradiated longer. Therefore, in the dose distribution B1, now dose distribution B1 rises sharply at the edges in the direction along the first irradiation line L ₁ (vertical direction in FIG. 4), a reduction in such edge portion It becomes possible to suppress.

Here, when the irradiation line L extends in a rectangular wave shape, as shown in FIG. 5C, the second irradiation line L ₂ is located on the end side of the first irradiation line L ₁ of the irradiation field F. A region 20 where the sigma exists and a region 21 where it does not exist are mixed. Therefore, in the conventional charged particle beam irradiation apparatus, as shown in FIG. 7A, an area where the dose of the irradiated charged particle beam R is large on the end side of the first irradiation line L ₁ of the irradiation field F is Unevenness with a small area is likely to occur (prone to spots).

In this regard, according to the charged particle beam irradiation apparatus 1, as described above, the control apparatus 6 performs the first irradiation at the scanning speed V ₂ when scanning the charged particle beam R along the second irradiation line L _2. It is faster than the scanning speeds V ₁₁ , V ₁₂ , and V _1n when scanning the charged particle beam along the line L ₁ . Therefore, as shown in FIG. 7 (b), it is possible to suppress the dose of the charged particle beam R irradiated along the second irradiation line L _2, the first end portion side of the irradiation line L ₁ of the radiation field F The occurrence of unevenness can be suppressed.

  As described above, according to the charged particle beam irradiation apparatus 1 of the first embodiment, the scanning speed V when the control apparatus 6 irradiates the charged particle beam along the irradiation line L is set to the side in the dose distribution of the charged particle beam R. Change so that the edges are corrected. Therefore, it is possible to control the edge of the dose distribution B1 without controlling the intensity of the charged particle beam R, and it is possible to easily suppress unevenness and lowering of the edge of the dose distribution B1.

  The charged particle beam irradiation apparatus 1 employs the cyclotron 2 that continuously generates the charged particle beam R as described above. This is effective in that the charged particle beam R is continuously irradiated along the irradiation line L as compared with the case where a synchrotron that generates the charged particle beam R intermittently (pulsed) is employed.

  Next, a charged particle beam irradiation apparatus according to the second embodiment of the present invention will be described. In the description of the present embodiment, differences from the charged particle beam irradiation apparatus 1 of the first embodiment will be mainly described.

As shown in FIG. 9, the irradiation line L10 has a third irradiation line L ₃ extending along the outer edge of the irradiation field F, the fourth irradiation line L ₄ located inside the third irradiation line L ₃ , Including. The fourth irradiation line L ₄ are, it includes a sixth irradiation line L ₆ similar to the irradiation line L ₁ and the same fifth irradiation line L _5, and irradiation line L ₂ of the above. The control device 6 controls the scanning electromagnets 5a and 5b to execute the following operations.

That is, first, as shown in FIG. 9 (a), continuous irradiation while scanning the charged particle beam R at a scanning speed V ₃ along the third irradiation line L ₃ (S21 in FIG. 8). The scanning speed V ₃ is set slower than the scanning speed V ₄ will be described later.

Subsequently, as shown in FIG. 9 (b), continuously irradiated while scanning the charged particle beam R at a scanning speed V ₄ along the fourth irradiation line L ₄ (S22). Specifically, the charged particle beam R is irradiated while scanning along the irradiation line L ₅ at a scanning speed V ₄₁ similar to the scanning speed V _12, and the scanning speed V similar to the scanning speed V ₂ described above. Irradiate while scanning along the irradiation line L ₆ at ₄₂ . Then, by repeating S22 a predetermined number of times, irradiation of the charged particle beam R along the irradiation line L10 in the irradiation field F is completed as shown in FIG.

As described above, in the charged particle beam irradiation apparatus of the present embodiment, the control device 6 sets the scanning speed V ₃ when irradiating the charged particle beam R along the third irradiation line L ₃ to the third irradiation line L ₃ . The scanning speed V ₄ (V ₄₁ and V ₄₂ ) when irradiating the charged particle beam R along the fourth irradiation line L ₄ that is the inner irradiation line is made slower. That is, the control device 6 uses the scanning speed when irradiating the charged particle beam R along the irradiation line at the edge in the dose distribution B1 and the irradiation speed when irradiating the charged particle beam R along the other irradiation lines. It is slower than the scanning speed. Therefore, the irradiation time of the charged particle beam R along the third irradiation line L ₃ becomes long, so that the charged particle beam R along the third irradiation line L ₃ is sufficiently illuminated. As a result, it is possible to easily suppress a decrease in the edge portion of the dose distribution B1.

  The preferred embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment.

  For example, as shown in FIG. 10A, continuous irradiation (so-called raster scanning) may be performed while scanning the charged particle beam R along the irradiation line L20 extending in a triangular wave shape in the irradiation field F. That is, the present invention can be applied to irradiation lines of any shape. Further, as shown in FIG. 10B, the irradiation line L30 is set so as to avoid a part of the irradiation field F (here, the central part), and the charged particles R are irradiated so as to avoid a part of the irradiation field F. May be. In this case, the edge portions of the dose distribution are an outer edge portion and an inner edge portion.

In the above embodiment, when irradiating a charged particle beam R to the position of the one end and the other end of the first irradiation line L _1, has been stopped during the scanning of a predetermined time, the scanning speed without stopping the scanning May be late. That is, in the one end and the other end of the first irradiation line L _11, may be slower than the scanning speed V _11, at the one end and the other end of the first irradiation line L ₁₂ may be slower than the scanning speed V ₁₂ The first irradiation line L _1n may be slower than the scanning speed V _1n at one end and the other end.

  Further, the positions where the monitors 4a and 4b are arranged are not limited to the positions in the above-described embodiment, and may of course be arranged at appropriate positions.

1 is a perspective view of a charged particle beam irradiation apparatus according to a first embodiment of the present invention. It is a schematic block diagram of the charged particle beam irradiation apparatus of FIG. It is a flowchart which shows operation | movement of the charged particle beam irradiation apparatus of FIG. It is a figure for demonstrating operation | movement of the charged particle beam irradiation apparatus of FIG. FIG. 5 is a diagram subsequent to FIG. 4. It is a diagram which shows the dose distribution in the cross section along the VI-VI line of FIG.5 (c). It is a diagram which shows the dose distribution in the cross section along the VII-VII line of FIG.5 (c). It is a flowchart which shows operation | movement of the charged particle beam irradiation apparatus which concerns on 2nd Embodiment of this invention. It is a figure for demonstrating operation | movement of the charged particle beam irradiation apparatus of FIG. It is a figure which shows the other example of an irradiation line.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Charged particle beam irradiation apparatus, 5a, 5b ... Scanning magnet, 6 ... Control apparatus (control means), 14 ... Tumor (irradiation object), F ... Irradiation field, L, L10, L20, L30 ... Irradiation line, L1 , L11 to L1n ... first irradiation line, L2 ... second irradiation line, L3 ... third irradiation line, L4 ... fourth irradiation line, L5 ... fifth irradiation line, L6 ... sixth irradiation line, R ... charged particle beam. .

Claims (8)

A charged particle beam irradiation apparatus for continuously irradiating a charged particle beam along an irradiation line in an irradiation field set on an irradiation object,
A scanning electromagnet for scanning the charged particle beam;
Control means for controlling the operation of the scanning electromagnet,
The control means changes a scanning speed when irradiating the charged particle beam along the irradiation line so that a marginal portion in a dose distribution of the charged particle beam is corrected. X-ray irradiation device. The irradiation line extends in a rectangular wave shape, and a plurality of first irradiation lines arranged in parallel at predetermined intervals and a plurality of adjacent one ends or the other ends of the adjacent first irradiation lines are connected. The charged particle beam irradiation apparatus according to claim 1, comprising a second irradiation line. The control means determines the scanning speed when irradiating the charged particle beam along the outer first irradiation line among the three or more rows of the first irradiation lines, and the charge along the other first irradiation lines. The charged particle beam irradiation apparatus according to claim 2, wherein the charged particle beam irradiation apparatus is slower than a scanning speed when the particle beam is irradiated.   The control means uses a scanning speed when irradiating the charged particle beam to the end portion of the first irradiation line, and a scanning speed when irradiating the charged particle beam to a portion other than the end portion of the first irradiation line. 4. The charged particle beam irradiation apparatus according to claim 2, wherein the charged particle beam irradiation apparatus is also delayed or set to 0 for a predetermined time.   The controller is configured to increase a scanning speed when scanning the charged particle beam along the second irradiation line to be higher than a scanning speed when scanning the charged particle beam along the first irradiation line. The charged particle beam irradiation apparatus according to any one of claims 2 to 4, wherein the charged particle beam irradiation apparatus is characterized. The control means has a scanning speed when irradiating the charged particle beam along an irradiation line at a peripheral portion in the dose distribution, and a scanning speed when irradiating the charged particle beam along other irradiation lines. The charged particle beam irradiation apparatus according to claim 1, wherein the charged particle beam irradiation apparatus is slower. The irradiation line includes a third irradiation line extending along an outer edge of the irradiation field, and a fourth irradiation line inside the third irradiation line,
The control means makes a scanning speed when scanning the charged particle beam along the third irradiation line slower than a scanning speed when scanning the charged particle beam along the fourth irradiation line. The charged particle beam irradiation apparatus according to claim 6. The fourth irradiation line extends in a rectangular wave shape, and connects three or more rows of fifth irradiation lines arranged in parallel at a predetermined interval to one end or the other end of the adjacent fifth irradiation lines. The charged particle beam irradiation apparatus according to claim 7, comprising a plurality of sixth irradiation lines.

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